Osteoarthritis (OA) of the knee occurs in a substantial portion of the population over the age of fifty. The substantial variation in the rate of initiation and progression of the disease can be influenced by normal variation in the in vivo function of the knee during locomotion. Yet the specific functional measures (kinematic and load) that produce adaptive vs. degenerative to the articular cartilage at the knee during ambulation are not well understood. The long-term goal of this study is to test a specific mechanism that relates in vivo knee function (kinematics and loading during locomotion) to the progression of osteoarthritis (OA) at the knee. As an initial step toward this goal, this project will test the overall hypothesis that regional variations in knee cartilage thickness (in an asymptomatic population with no history of soft tissue injury at the knee) are related to specific kinematic and loading characteristic at the knee during walking. The following Specific Aims will be addressed: (1) to evaluate the relationship between loading at the knee during locomotion and regional variations in cartilage thickness; (2) to evaluate the relationship between a positional offset at the knee during locomotion and regional variations in cartilage thickness; and (3) to evaluate the relationship between motion at the knee during locomotion and regional variations in cartilage thickness. The methods to test the hypotheses will combine state-of-the-art methods for the analysis of human movement, and magnetic resonance imaging (MRI) techniques to quantify femoral and tibial cartilage thickness. A population of asymptomatic subjects (stratified by ages between 20 and 70 years) will be tested studied using a cross-sectional study design. The results of this study will address important unanswered questions on the kinematic and morphological factors that can influence the degradation of the articular cartilage. Information on the relative importance of loading and motion during walking will provide fundamental new information that can ultimately be applied to prevention and treatment of knee OA. [unreadable] [unreadable]